Denial of service in Open5GS PFCP transaction handling

A denial-of-service vulnerability exists in open5GS v2.8.0 in the PFCP transaction handling path. When the PFCP transaction or timer resource pool is exhausted, ogs_pfcp_xact_remote_create() returns NULL, but the failure is not handled properly and leads to an ogs_assert(new) failure in ogs_pfcp_xact_receive(). An attacker able to send PFCP messages to the affected SMF/UPF can exhaust transaction resources and cause the network function process to terminate with SIGABRT, resulting in service disruption and preventing further session establishment until the affected component is restarted.